A folding container is conventionally known which includes long side walls coupled, via hinge members, to respective opposite long side portions of a bottom portion formed so as to have a substantially rectangular planar shape, and short side walls also coupled, via hinge members, to respective opposite short side portions of the bottom portion. The folding container is assembled into box form by raising the long side walls and the short side walls substantially perpendicularly to the bottom portion. Furthermore, when the folding container is folded, the long side walls and the short side walls are folded so as to overlap the bottom portion. When the folding container is in assembled box form, the long side walls or the short side walls are locked by lock members so as not to fall down toward the bottom portion.
For example, U.S. Pat. No. 6,290,081 discloses a lock member disposed on a short side wall and including one operation portion movable along the wall surface of the short side wall, paired lock bars movable in a horizontal direction, and a vertical motion-horizontal motion conversion mechanism composed of inclined cam grooves formed in the respective lock bars and a driven short shaft projected from the operation portion, the vertical motion-horizontal motion conversion mechanism converting vertical motion of the operation portion into horizontal motion of the lock bars.
If the operation portion is located at a lower position, the tip portion of each of the lock bars is inserted into a fitting recess portion formed in the corresponding long side wall. Thus, each of the short side walls is locked on the long side walls via the lock members so as not to fall down toward the bottom portion. Furthermore, the operation portion located at the lower position is moved upward along the wall surface of the short side wall to move the paired lock bars closer to each other in the horizontal direction. This allows the tip portions of the lock bars to be discharged from the fitting recess portions formed in the respective long side walls. Consequently, the lock state is cancelled in which the short side walls are locked on the long side walls via the lock members. Therefore, the short side walls can be brought down so as to overlap the bottom portion.
According to the above-described conventional folding container, to fold the folding container assembled in box form, an operator moves the operation portion upward. However, depending on the position of the operator's hand with respect to the operation portion, the operation portion fails to maintain a horizontal state but is inclined while being moved upward. If the operation portion is inclined while being moved upward, the operation portion hinders smooth horizontal movement of the paired lock bars coupled together via the vertical motion-horizontal motion conversion mechanisms. This may disadvantageously prevent the reliable cancelation of the lock state in which the long side walls are locked on the short side walls via the vertical motion-horizontal motion conversion mechanisms.
Furthermore, a handling through-hole into which the operator's hand is inserted in order to carry the folding container assembled in box form is located close to an operation portion operating recess portion into which the operator places the hand in order to move the operation portion of the lock member upward or downward. Thus, when carrying the folding container assembled in box form, the operator may inadvertently place the hand in the operation portion operating recess portion to move the operation portion upward to cancel the lock state of the short side walls and the long side walls.
Moreover, the paired lock bars are horizontally moved via the vertical motion-horizontal motion conversion mechanism. Hence, a strong force is required to move the lock bars in the horizontal direction. This may disadvantageously prevent operations of folding and assembling the folding container from being properly performed.
Furthermore, when the folding container is in assembled box form, the operation portion, and a leaf spring and the vertical motion-horizontal motion conversion mechanism which are included in the operation portion are arranged in the operation portion operating recess portion that is open to the outside of the short side wall. Thus, an external member may be inadvertently placed in the operation portion operating recess portion, thus damaging the operation portion and the leaf spring and vertical motion-horizontal motion conversion mechanism which are included in the operation portion.
An object of the present invention is to solve the above-described problems with the conventional folding container.